Diagnostics

LR-BPM

Log-Ratio BPM Electronics

Non-intercepting beam position measurement

Optimal for single-pass short bunches

Beam charge range

> 50 dB

Repetition frequency

≤ 500 MHz

Principle

Based on the pioneering work of Robert E. Shafer at Los Alamos Laboratory,the Log-Ratio BPM derives beam position from logarithm of the ratio of opposite pickup signals: Log(A/B).Position measured by this method is more linear, over a wider range, than difference-over-sum.

Signal processing

Signals from the pickups are stretched to produce bursts. This is essential to measure the single pass of a bunch.Four parallel logarithmic amplifiers detect the burst envelopes. Amplifiers’ response is log of amplitude.Logs of opposite pickups are subtracted.If pickups are rotated, axes are translated to obtain X and Y positions.The process is all-analog, wideband.

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Features

The Log-Ratio Beam Position Monitor (LR-BPM) is an electronics module for fast analog processing of beam pickups signals.